In a computed tomography device (CT), the data transmission between the permanently fixed mounting frame and the rotating assembly (“gantry”) rotating relative thereto assumes an important role. On the one hand the individual items of image data generated are to be transmitted from the gantry to the mounting frame, in order to be able to forward them from there to the central image processing facility, and ultimately to provide the medical personnel with a sufficiently meaningful overall image. On the other hand data, in particular control data, is frequently also to be transmitted from the mounting frame to the rotating assembly during ongoing operation.
In a CT, data transmission between the gantry and the mounting frame frequently takes place via slip rings. As a result of the direct physical contact which is created for the transmission between a ring on the gantry and the sliding contacts on the mounting frame, these display an inherent abrasion, which over the course of long-term operation can impair the stability of the transmission, and may thus have to be compensated for. In addition the friction is increased by the physical contact, so that an increased energy demand for the rotation itself may arise, which is generally unwelcome.
The ever-increasing data volumes resulting from the higher resolution in the case of the imaging, and the requirements arising in terms of the data rate for the transmission pose a problem which has yet to be solved. One approach is to improve the data rates through the use of directional couplers, which are based on dielectric waveguides. The transmission here takes place essentially through the electromagnetic, in particular optical coupling-in of a signal, which is guided to the gantry by way of a dielectric waveguide, across the air gap into a further dielectric waveguide on the mounting frame.